He said they were three friends heading for a reunion in Paris when they "ended up engaging a potential catastrophic situation and pinning down someone who clearly was intent on doing a lot of harm to a lot of people, inflicting terror on the French people".

The three sat attentively on an Oval Office couch and chair as the president praised them as "the very best of America".

When they were awarded France's highest honour by President Francois Hollande they showed up for the hastily scheduled ceremony at the ornate Elysee Palace in polo shirts and khakis.

This time, Oregon National Guardsman Mr Skarlatos and Airman 1st Class Stone were in military uniform, and Mr Sadler, a student at Sacramento State University, wore a sports coat and open-collared dress shirt.

"It's these kinds of young people who make me extraordinarily optimistic about the future," Mr Obama said.

The three last month subdued a man with ties to radical Islam who boarded the train with a Kalashnikov rifle, a pistol and a box cutter.

British businessman Chris Norman and a French-American have also been praised for their efforts to stop the gunman.